/*
 * Error routines for programs that can run as a daemon.
 */

#include "../apue.h"
#include <errno.h>      /* for definition of errno */
#include <stdarg.h>     /* ISO C variable arguments */
#include <syslog.h>

static void log_doit(int, int, const char *, va_list ap);

/*
 * Caller must define and set this: nonzero if
 * interactive, zero if daemon
 */
extern int log_to_stderr;

/*
 * Initialize syslog(), if running as daemon.
 */
void
log_open(const char *ident, int option, int facility)
{
    if (log_to_stderr == 0)
        openlog(ident, option, facility);
}

/*
 * Nonfatal error related to a system call.
 * Print a message with the system's errno value and return.
 */
void
log_ret(const char *fmt, ...)
{
    va_list     ap;
    va_start(ap, fmt);
    log_doit(1, LOG_ERR, fmt, ap);
    va_end(ap);
}

/*
 * Fatal error related to a system call.
 * Print a message and terminate.
 */
void
log_sys(const char *fmt, ...)
{
    va_list     ap;

    va_start(ap, fmt);
    log_doit(1, LOG_ERR, fmt, ap);
    va_end(ap);
    exit(2);
}

/*
 * Nonfatal error unrelated to a system call.
 * Print a message and return.
 */
void
log_msg(const char *fmt, ...)
{
    va_list ap;

    va_start(ap, fmt);
    log_doit(0, LOG_ERR, fmt, ap);
    va_end(ap);
}

/*
 * Fatal error unrelated to a system call.
 * Print a message and terminate.
 */
void
log_quit(const char *fmt, ...)
{
    va_list     ap;

    va_start(ap, fmt);
    log_doit(0, LOG_ERR, fmt, ap);
    va_end(ap);
    exit(2);
}

/*
 * Print a message and return to caller.
 * Caller specifies "errnoflag" and "priority".
 */
static void
log_doit(int errnoflag, int priority, const char *fmt, va_list ap)
{
    int     errno_save;
    char    buf[MAXLINE];

    errno_save = errno;     /* value caller might want printed */
    vsnprintf(buf, MAXLINE, fmt, ap);
    if (errnoflag)
        snprintf(buf+strlen(buf), MAXLINE-strlen(buf), ": %s",
          strerror(errno_save));
    strcat(buf, "\n");
    if (log_to_stderr) {
        fflush(stdout);
        fputs(buf, stderr);
        fflush(stderr);
    } else {
        syslog(priority, buf);
    }
}
